I tried searching but couldnt find anything. I have heard of stress cuts for log manifold but am not quite sure where they are cut. Can someone please enlighten me?
Stress cuts are placed in the flange between the runners so that each cylinder can heat and cool down / expand and contract at different rates without warping the flange or cracking.
-Chris-
-Sweetness-
-Turbocharged-
Slowly but surely may some day win this race...
so you can and
should do it to every log manifold???
I must confess... I feel like a monster!
I would think this would just cause the runners to crack...
the stock eco exhaust manifold is cut from the GM check it out if you need a visual
JBO since July 30, 2001
The idea behind stress cuts are to give some heat transfer away in an effort to gain some flexibility. Definitely worth it, especially since heat transfer will primarily all be thru the runners and the head anyway and in those area nothing will change. So you almost seem to get the flexibility without any/much change in heat transfer across the flange.
"Never argue with an idiot. They'll drag you down to their level, then beat you with experience!" -Anonymous
If the runners are separate then it's not a log manifold and you can make the stress cuts to your advantage on the flange.
True "Log" manifolds have a shared dump into a single opening (log) - so no , you can't and don't need to make stress cuts.
^No.
Given the added rigidity of a log manifold, stress cuts are more important then in other types of manifolds. If your running a runner style manifold it will have more flexibility when it comes the heat expansion.
"Never argue with an idiot. They'll drag you down to their level, then beat you with experience!" -Anonymous
I agree but I have a very short log type manifold - I highly doubt that it could be cut. There's basically no runner length at all. The cylinders just dump straight into the log.
there should be the same amount of room for stress cuts on any manifold more or less since they go on the flange. The reason they are so important on the log is because the flange expands long-ways and the pipe log itself which is very close to the flange will expand long-ways too...but not as much as the flange, especially at the ends where they use the 90 degree bends for the first and last cylinders. You can solve this with selective material selection but given the heat and such, alot of the simple metallurgic solutions aren't compatible with the heat. So the cheapest solution is stress cut the flange to allow expansion.
"Never argue with an idiot. They'll drag you down to their level, then beat you with experience!" -Anonymous
I agree - good info and great explanation. I have a one piece cast log - so I believe this is bit different than the steel pipe log type manifolds.
